A motor vehicle steering column must conventionally provide three functions:
1. transmit a force between the steering wheel and the steering system to enable the rotation of the wheels when the steering wheel is turned,
2. adjust the height and depth of the position of the steering wheel in the vehicle,
3. retract while absorbing the energy of the driver in the case of an accident.
There are presently known on the market steering columns in which are present three independent complex devices to provide each of the three above-mentioned functions. Since these three devices require a set of complex, bulky components, the manufacturing costs of such a steering column are relatively high. Moreover, the present bulk-reduction requirements mean that it is necessary to provide systems performing these three functions and presenting the smallest dimensions possible.
Known already is U.S. Pat. No. 6,234,528, which describes an adjustable energy absorption device for a motor vehicle steering column. This type of energy absorption system functions well but requires the creation of supplementary parts including a multiplicity of deformable parts absorbing the energy upon their deformations which must be attached by the intermediary of other elements to the steering column. This energy absorption system is therefore expensive. Moreover, this system requires the installation of a multiplicity of parts at the level of or close to the steering column. This has a negative impact to the extent that gaining space is essential not only to facilitate their installation, but also to allow the placement of other materials.
FR 2714649 describes an energy absorption component interposed between two elements capable of moving away from each other under the action of an external forces. The component comprises a first part extending around a support shaft mounted on a first element and a second rectilinear part extending the first part having a free end fixed on the second element and extending between the two elements while being oriented essentially in the direction of the force. The component also includes a wire coiled into joined spires constituting a coil positioned around the support shaft of the first element such that the traction exerted on the wire by the moving apart of the two elements causes the unwinding of the coil around the support shaft and thus the required absorption of energy.
Also known is JP 2001 334944 which endeavors to reduce the number of parts required for the implementation of an energy absorption device for a steering column in a manner that is both effective and inexpensive. In that system, the impact absorption part comprises a rotary device mounted on one of the elements of the steering column, a component capable of rotating around the horizontal axis between the steering column element and the body of the motor vehicle, a linear component linked to the rotary device and having its two ends fixed to the rotary device, and a fixed engagement hook of the other side of the steering column element and engaged with the central part of the linear component.
When an impact occurs, the engagement hook pulls the part linked to the rotary device of the linear component to plastically deform this part of the linear component and then drive in rotation the rotary device so as to absorb the energy of the impact. It can be understood that despite the desire to create an energy absorption device comprising a small number of elements, that device remains very complex and thus costly.
It is in fact very difficult to envision the creation of a simple, inexpensive energy absorption device that can satisfy all of the requirements imposed by the automobile manufacturers and dealers.
JP 3279085 discloses an energy absorption device for steering columns comprising an additional element as well as sliding guides fixed on the steering column. That device is complex both because of its creation and its attachment to the steering column. It is also bulky because it occupies a considerable amount of space.